System for chemical mechanical polishing of ge-based materials and devices

ABSTRACT

A CMP slurry composition which provides for a high Ge- or SiGe-to-dielectric material selectivity a low rate of Ge or SiGe recess formation includes an oxidant and a germanium removal rate enhancer including at least one of a methylpyridine compound and a methylpyridine derivative compound. In some examples, the slurry composition also includes an etching inhibitor. In some cases, the slurry composition may include an abrasive, a surfactant, an organic complexant, a chelating agent, an organic or inorganic acid, an organic or inorganic base, a corrosion inhibitor, or a buffer. The slurry composition may be distributed onto a surface of a polishing pad disposed on a platen that is configured to rotate. Additionally, a workpiece carrier configured to house a substrate may bring the substrate into contact with the rotating polishing pad and thereby polish the substrate utilizing the slurry composition.

PRIORITY DATA

The present application is a divisional patent application of U.S.patent application Ser. No. 15/381,022 filed on Dec. 15, 2016, whichwill issue as U.S. Pat. No. 9,994,736, which is a divisional patentapplication of U.S. patent application Ser. No. 14/480,046 filed on Sep.8, 2014, now U.S. Pat. No. 9,530,655, the disclosures of which arehereby incorporated by reference in their entirety.

BACKGROUND

The electronics industry has experienced an ever increasing demand forsmaller and faster electronic devices which are simultaneously able tosupport a greater number of increasingly complex and sophisticatedfunctions. Accordingly, there is a continuing trend in the semiconductorindustry to manufacture low-cost, high-performance, and low-powerintegrated circuits (ICs). Thus far these goals have been achieved inlarge part by scaling down semiconductor IC dimensions (e.g., minimumfeature size) and thereby improving production efficiency and loweringassociated costs. However, such scaling has also introduced increasedcomplexity to the semiconductor manufacturing process. Thus, therealization of continued advances in semiconductor ICs and devices callsfor similar advances in semiconductor manufacturing processes andtechnology.

A particular challenge, and one which has become increasingly difficultfor reduced device geometries, relates to the substrate planarizationrequirements during device fabrication. To meet such requirements,chemical mechanical polishing (CMP) is a process that has beenintroduced and used throughout the semiconductor industry, and whichcontinues to be developed. In a conventional CMP process, a substratesurface is acted upon by a slurry and a polishing pad. By way ofexample, a force may be applied to press the substrate against the padwhile the substrate and the pad are rotated. The rotation and thesubstrate-to-pad force, in conjunction with the slurry supplied to thesubstrate, serve to remove substrate material and thus planarize asurface of the substrate. In general, a CMP process should be optimizedfor specific process conditions such as the material being polished,device structure, desired etch rate, etc. With the continued advancementof highly-scaled IC technology, bringing with it new materials and newdevice structures, optimization of CMP processes not proved entirelysatisfactory in all respects.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the followingdetailed description when read with the accompanying figures. It isnoted that, in accordance with the standard practice in the industry,various features are not drawn to scale. In fact, the dimensions of thevarious features may be arbitrarily increased or reduced for clarity ofdiscussion.

FIG. 1A illustrates a chemical mechanical polishing (CMP) systemaccording to one or more aspects of the present disclosure;

FIG. 1B illustrates a CMP slurry manufacturing and delivery systemaccording to one or more aspects of the present disclosure;

FIGS. 2A-2C illustrate isomers of methylpyridine which may be used as Geremoval rate enhancer within a CMP slurry according to one or moreaspects of the present disclosure;

FIGS. 3A-3D illustrate methylpyridine derivative compounds which may beused as a Ge removal rate enhancer within a CMP slurry according to oneor more aspects of the present disclosure;

FIG. 4 illustrates a table of some embodiments of slurry compositionswhich include a Ge removal rate enhancer;

FIG. 5 illustrates a table of some embodiments of slurry compositionswhich include a Ge removal rate enhancer and an etching inhibitor;

FIG. 6 illustrates an example of a mechanism by which embodiments of theCMP slurry provide their described functionality;

FIG. 7 is a flow chart of a method of performing a CMP process accordingto one or more aspects of the present disclosure;

FIG. 8 is a flow chart of a method of fabricating a semiconductor deviceincluding performing a CMP process according to one or more aspects ofthe present disclosure;

FIGS. 9-13 illustrate cross-section views of an embodiment of asemiconductor device at various stages of the method of FIG. 8; and

FIG. 14 illustrates a perspective view of an embodiment of asemiconductor device at a stage of the method of FIG. 8.

DETAILED DESCRIPTION

The following disclosure provides many different embodiments, orexamples, for implementing different features of the provided subjectmatter. Specific examples of components and arrangements are describedbelow to simplify the present disclosure. These are, of course, merelyexamples and are not intended to be limiting. For example, the formationof a first feature over or on a second feature in the description thatfollows may include embodiments in which the first and second featuresare formed in direct contact, and may also include embodiments in whichadditional features may be formed between the first and second features,such that the first and second features may not be in direct contact. Inaddition, the present disclosure may repeat reference numerals and/orletters in the various examples. This repetition is for the purpose ofsimplicity and clarity and does not in itself dictate a relationshipbetween the various embodiments and/or configurations discussed.

Further, spatially relative terms, such as “beneath,” “below,” “lower,”“above,” “upper” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. The spatiallyrelative terms are intended to encompass different orientations of thedevice in use or operation in addition to the orientation depicted inthe figures. The apparatus may be otherwise oriented (rotated 90 degreesor at other orientations) and the spatially relative descriptors usedherein may likewise be interpreted accordingly.

It is also noted that the present disclosure presents embodiments ofchemical mechanical polishing (CMP) processes, including CMP slurries,useful for the fabrication of multi-gate transistors or fin-typemulti-gate transistors referred to herein as FinFET devices. Such adevice may include a P-type metal-oxide-semiconductor FinFET device oran N-type metal-oxide-semiconductor FinFET device. The FinFET device maybe a dual-gate device, tri-gate device, bulk device,silicon-on-insulator (SOI) device, and/or other configuration. One ofordinary skill may recognize other examples of semiconductor devicesthat may benefit from aspects of the present disclosure. For example,some embodiments as described herein may also be applied to planartransistors, gate-all-around (GAA) devices, Omega-gate (Ω-gate) devices,or Pi-gate (H-gate) devices. While the CMP slurries and processes aredescribed herein with reference to multi-gate or FinFET devices, it willbe understood that the slurries and processes described herein are notlimited to such devices and may be equally applied to the fabrication ofother devices (e.g., planar CMOS devices) without departing from thescope of the present disclosure.

As semiconductor device sizes continue to shrink, it has becomeincreasingly difficult to meet device planarization requirements infabrication. For example, the formation of fin elements as part of aFinFET device fabrication process generally requires a planarizationstep. In particular, CMP planarization of germanium (Ge) or silicongermanium (SiGe) has introduced new challenges to FinFET fabrication.Traditionally, the CMP planarization step used for example in theformation of Ge or SiGe fin elements (e.g., for a FinFET device), mayuse a slurry comprising hydrogen peroxide. As used herein, a “slurry”includes an aqueous mixture having a chemical composition that mayenhance, reduce, or otherwise modify a substrate polishing rate. In somecases, slurries may also contain abrasive particles. In variousexamples, traditional hydrogen peroxide slurries may provide adesirable, high germanium-to-oxide selectivity (i.e., preferentialremoval of germanium instead of oxide). However, such slurries may alsoexcessively recess the germanium fin elements, which may include channelregions of a FinFET device, and which can thus negatively impact deviceperformance. Therefore, a CMP process that uses a slurry having a highgermanium-to-oxide selectivity, as well as a low rate of germaniumrecess formation, is desirable for the successful implementation of Ge-or SiGe-based FinFET devices.

According to various aspects of the present disclosure, an improved CMPslurry composition is disclosed, which provides for a high Ge- orSiGe-to-dielectric material selectivity along with a low rate of Ge orSiGe recess formation. In some embodiments, the disclosed slurrycomposition includes an oxidant and a Ge removal rate enhancer. In someembodiments, the oxidant includes a compound having one or more oxygenmolecules. In some embodiments, the Ge removal rate enhancer includes amethylpyridine compound or a methylpyridine derivative compound. In thevarious embodiments described herein, the slurry compositions includingthe Ge removal rate enhancer provides a high polishing throughput (e.g.,via high Ge or SiGe removal), a low rate of Ge or SiGe recess formation,and an enhanced pot-life (i.e., time period during which the slurrycomposition retains its efficacy). While a few advantages of certainembodiments described herein have been described, those skilled in theart will readily recognize other advantages of using one or more of thepresent embodiments.

Referring to the example of FIG. 1A, a chemical mechanical polishing(CMP) system 100 is illustrated. The CMP system 100 includes a slurrysource 102 configured to distribute a slurry 104 onto a surface of apolishing pad 106. As shown in FIG. 1A, the polishing pad 106 isdisposed on a platen 108, which rotates the polishing pad 106 about anaxis of rotation 110 during operation of the CMP system 100. Therotation of the polishing pad 106 transports the slurry 104 underneath asemiconductor substrate 112. Thus, the polishing pad 106, in conjunctionwith the slurry 104, serves to polish the substrate 112. A padconditioner 114, which may include a diamond grit conditioning pad, isconfigured to push on the polishing pad 106 with a downward force suchthat the diamond grit is brought into contact with the polishing pad106. As the polishing pad 106 is rotated by the platen 108, the diamondgrit roughens the surface of the polishing pad 106 to provide forimproved mechanical polishing. It is noted that this description of FIG.1A is exemplary only and it should be understood that other embodimentsof a CMP system and removal mechanism are within the scope of thepresent disclosure.

The CMP system 100 further includes a workpiece carrier 116 that isconfigured to house the substrate 112 during the CMP process. In variousembodiments, the substrate 112 is positioned in an upside downorientation within the workpiece carrier 116 so that a top surface ofthe substrate 112 faces the polishing pad 106. By way of example, theworkpiece carrier 116 is operable to bring the substrate 112 intocontact with the polishing pad 106, for example, such that the topsurface of the substrate 112 contacts the polishing pad 106 while thepolishing pad 106 rotates. By bringing the semiconductor substrate 112into contact with the rotating polishing pad 106, polishing of thesubstrate 112 is achieved. Additionally, in some embodiments, theworkpiece carrier 116 may also be rotated during operation of the CMPsystem 100 for example, about an axis of rotation 120.

In various embodiments, the substrate 112 may include one or more layers118 to be polished, such as a dielectric material layer (e.g., oxide), ametal layer, a semiconductor layer (e.g., silicon, germanium, a III-Vsemiconductor material), or a combination thereof. The one or morelayers 118 include an interface that directly faces the rotatingpolishing pad 106. In some embodiments, the one or more layers 118includes germanium (Ge) or Si_((1-x))Ge_(x), where ‘x’ includes valuesfrom around 15% to around 100%. Thus, in some embodiments, the layer 118may include a SiGe layer with around 15% Ge, a SiGe layer with around100% Ge (i.e., pure Ge), or a SiGe layer having any Ge concentrationbetween 15-100%. In some examples, the one or more layers 118 mayinclude other materials (e.g., copper, aluminum, dielectrics, etc.). Byway of example, in some embodiments, the layer 118 includes a dielectricmaterial layer such as silicon dioxide. In various embodiments, such aswhen Ge or SiGe fin elements are being formed (e.g., as part of FinFETdevice fabrication), as described below, the one or more layers 118 mayinclude a Ge or SiGe layer as well as a dielectric layer (e.g., ashallow trench isolation oxide layer). In such embodiments, the CMPsystem 100 is configured to polish the Ge or SiGe layer, of the layer118, with a high Ge- or SiGe-to-dielectric material selectivity alongwith a low rate of Ge or SiGe recess formation.

In some embodiments, the CMP system 100 may be implemented within a CMPslurry manufacturing and delivery system 150, as illustrated in FIG. 1B.As shown, the CMP slurry manufacturing and delivery system 150 mayinclude a slurry manufacturing tank 152, one or more slurry storagetanks 154, a slurry day tank 156, an oxidant source 158, a Ge removalrate (R.R.) enhancer source 160, an etching inhibitor source 162, and/orother components as known in the art. In some embodiments, the slurrymanufacturing tank 152 is coupled to the oxidant source 158, the Geremoval rate enhancer source 160, and to the etching inhibitor source162. In various embodiments, the oxidant source 158 is configured toprovide an oxidant to the slurry manufacturing tank 152. In someembodiments, the oxidant provided by the oxidant source 158 may includea compound having one or more oxygen molecules such as hydrogenperoxide, or others as described below. In various embodiments, the GeR.R. enhancer source 160 is configured to provide a Ge removal rateenhancer to the slurry manufacturing tank 152. By way of example, insome embodiments, the Ge removal rate enhancer provided by the Ge R.R.enhancer source 160 may include a methylpyridine compound or amethylpyridine derivative compound as described below. In someembodiments, the etching inhibitor source 162 is configured to providean etching inhibitor to the slurry manufacturing tank 152. For example,in some embodiments, the etching inhibitor provided by the etchinginhibitor source 162 includes 2-mercaptopyridine N-oxide, or others asknown in the art. In some embodiments, the slurry manufacturing tank 152may also include one or more inlets 155 configured to provide de-ionizedwater (DIW) and/or abrasives to the slurry manufacturing tank 152, whichare subsequently introduced into the slurry. In some cases, inlets mayalso be provided to deliver one or more of an organic complexant, achelating agent, an organic or inorganic acid/base, a corrosioninhibitor, and a buffer.

In some embodiments, the slurry (e.g., stored in the slurry storage tank154) may be transported into the slurry day tank 156. In someembodiments, the slurry is provided by way of a transport piping 165from the slurry day tank 156 to one or more valve manifold boxes (VMB)164. The valve manifold boxes 164 are configured to selectively providethe slurry from the transport piping 165 to the CMP system 100, forexample, when the CMP system 100 is operated to perform a chemicalmechanical polishing of a substrate. In some embodiments, are-circulation transport piping 167 is configured to return slurry thathas not been provided to the CMP system 100 from the one or more valvemanifold boxes 164 to the slurry day tank 156. The slurry day tank 156is configured to mix the unused slurry with new slurry to maintain aslurry having a high Ge- or SiGe-to oxide selectivity with a low rate ofGe or SiGe recess formation. In various embodiments, the methylpyridineor methylpyridine derivative compounds extend the life of the slurry(e.g., the slurry within the day tank 156). In some examples, the slurrymaintains its efficacy for a time period of at least six months.

Returning to the slurry source 102 of FIG. 1A, and the slurry 104distributed therefrom, the slurry 104 includes an aqueous mixture havinga chemical composition that may enhance, reduce, or otherwise modify apolishing rate of the one or more layers 118. In some embodiments, theslurry 104 includes an oxidant (e.g., provided by the oxidant source158) and a Ge removal rate enhancer (e.g., provided by the Ge R.R.enhancer source 160). In some examples, the oxidant includes a compoundhaving one or more oxygen molecules such as hydrogen peroxide, potassiumperoxodisulfate, ammonium peroxodisulfate, sodium peroxodisulfate,potassium peroxymonosulfate, peracetic acid, or tert-butyl hydrogenperoxide. In some embodiments, the Ge removal rate enhancer includes amethylpyridine compound or a methylpyridine derivative compound. By wayof the example, the Ge removal rate enhancer may include2-methylpyridine; 3-methylpyridine; 4-methylpyridine;2,3-dimethylpyridine; 2,4-dimethylpyridine; 2,6-dimethylpyridine; or3,5-dimethylpyridine. In some embodiments, the slurry 104 includes anoxidant concentration from about 10 parts per million (ppm) to about50,000 ppm. In some embodiments, the slurry includes a Ge removal rateenhancer concentration from about 100 ppm to about 5,000 ppm. In someexamples, the slurry 104 has a pH value from about 1 to about 6.

It will be appreciated that in some embodiments the disclosed slurry 104may comprise additional components. For example, in some embodiments,the slurry 104 may include a surfactant (e.g., polyethylene glycol)configured to lower a surface tension of the slurry 104. In otherembodiments, the slurry 104 may include abrasive particles that aid inthe mechanical polishing of the semiconductor substrate 112. Forexample, the slurry 104 may include abrasive particles such as colloidalsilica, fumed silica, aluminum oxide, silica shell based compositesubmicron particles, ceria, etc. In other embodiments, the slurry 104may be abrasive free (i.e., the slurry 104 does not include abrasiveparticles). In addition, in some embodiments, the slurry 104 may includeat least one of organic complexants, chelating agents, organic orinorganic acids/bases, corrosion inhibitors, buffers, and etchinhibitors.

Expanding upon the composition of the slurry 104, and with reference toFIG. 2, some embodiments of methylpyridine compounds used as the Geremoval rate enhancer are illustrated. In particular, FIGS. 2A, 2B, and2C illustrate three different methylpyridine isomers. FIG. 2Aillustrates 2-methylpyridine, also known as 2-picoline and having thechemical formula C₆H₇N, which may be combined with one or more of theoxidants discussed above (e.g., hydrogen peroxide, potassiumperoxodisulfate, etc.) in an aqueous mixture to form the slurry 104.FIG. 2B illustrates 3-methylpyridine, also known as 3-picoline andhaving the chemical formula C₆H₇N, which may be combined with one ormore of the oxidants discussed above in an aqueous mixture to form theslurry 104. FIG. 2C illustrates 4-methylpyridine, also known as4-picoline and having the chemical formula C₆H₇N, which may be combinedwith one or more of the oxidants discussed above to form the slurry 104.

Further expanding upon the composition of the slurry 104, and withreference to FIG. 3, some embodiments of methylpyridine derivativecompounds used as the Ge removal rate enhancer are illustrated. FIG. 3Aillustrates 2,3-dimethylpyridine, also known as 2,3-lutidine and havingthe chemical formula C₇H₉N, which may be combined with one or more ofthe oxidants discussed above to form the slurry 104. FIG. 3B illustrates2,4-dimethylpyridine, also known as 2,4-lutidine and having the chemicalformula C₇H₉N, which may be combined with one or more of the oxidantsdiscussed above to form the slurry 104. FIG. 3C illustrates2,6-dimethylpyridine, also known as 2,6-lutidine and having the chemicalformula C₇H₉N, which may be combined with one or more of the oxidantsdiscussed above to form the slurry 104. FIG. 3D illustrates3,5-dimethylpyridine, also known as 3,5-lutidine and having the chemicalformula C₇H₉N, which may be combined with one or more of the oxidantsdiscussed above to form the slurry 104.

As discussed above, the slurry 104 may include an oxidant concentrationin the range of between about 10-50,000 ppm and a Ge removal rateenhancer concentration in the range of between about 100-5,000 ppm.Merely by way of example, some embodiments of the slurry 104 compositioninclude about 2,000 ppm colloidal silica, about 1,000 ppm H₂O₂, about200 ppm polyethylene glycol, about 500 ppm of a methylpyridine compoundor a methylpyridine derivative compound (described above), and have a pHlevel of about 3. In some embodiments, the slurry 104 compositionincludes about 2,000 ppm colloidal silica, about 1,000 ppm H₂O₂, about200 ppm polyethylene glycol, about 2,000 ppm of a methylpyridinecompound or a methylpyridine derivative compound, and have a pH level ofabout 3.

Referring to FIG. 4, a table 400 shows a germanium removal rate (GeR.R.) in angstroms per minute (A/min), an oxide removal rate (OxideR.R.) in A/min, and a germanium removal rate improvement percent forembodiments of a slurry 104 composition employing about 500 ppm of amethylpyridine compound or a methylpyridine derivative compound versusembodiments of the slurry 104 composition employing about 2,000 ppm of amethylpyridine compound or a methylpyridine derivative compound. Forcomparison, the first row of the table 400 shows data for a controlslurry composition, which does not include the Ge removal rate enhancer.By way of example, the control slurry composition may include about2,000 ppm colloidal silica, about 1,000 ppm H₂O₂, about 200 ppmpolyethylene glycol, and have a pH level of about 3. As shown in thetable 400, the control slurry composition has a Ge R.R. of about 2,200Å/min and an Oxide R.R. of about 80 Å/min.

With reference now to the example slurry 104 compositions having the Geremoval rate enhancer, the second row of the table 400 illustrates afirst example (Example 1) which includes 2-methylpyridine as the Geremoval rate enhancer. As shown, the slurry 104 composition with 500 ppm2-methylpyridine provides for a Ge R.R. of about 3,332 Å/min and anOxide R.R. of about 95 Å/min, resulting in about a 51% Ge R.R.improvement over the control slurry composition. As also shown, theslurry 104 composition with 2.00 ppm 2-methylpyridine provides for a GeR.R. of about 3,521 Å/min and an Oxide R.R. of about 96 Å/min, resultingin about a 60% Ge R.R. improvement over the control slurry composition.

As another example, the third row of the table 400 illustrates a secondexample (Example 2) which includes 3-methylpyridine as the Ge removalrate enhancer. As shown, the slurry 104 composition with 500 ppm3-methylpyridine provides for a Ge R.R. of about 2,354 Å/min and anOxide R.R. of about 97 Å/min, resulting in about a 7% Ge R.R.improvement over the control slurry composition. As also shown, theslurry 104 composition with 2.00 ppm 3-methylpyridine provides for a GeR.R. of about 2,398 Å/min and an Oxide R.R. of about 94 Å/min, resultingin about a 9% Ge R.R. improvement over the control slurry composition.

The fourth row of the table 400 illustrates a third example (Example 3)which includes 4-methylpyridine as the Ge removal rate enhancer. Asshown, the slurry 104 composition with 500 ppm 4-methylpyridine providesfor a Ge R.R. of about 3,478 Å/min and an Oxide R.R. of about 96 Å/min,resulting in about a 58% Ge R.R. improvement over the control slurrycomposition. As also shown, the slurry 104 composition with 2.00 ppm4-methylpyridine provides for a Ge R.R. of about 3,564 Å/min and anOxide R.R. of about 97 Å/min, resulting in about a 62% Ge R.R.improvement over the control slurry composition.

Continuing with example slurry 104 compositions having the Ge removalrate enhancer, the fifth row of the table 400 illustrates a fourthexample (Example 4) which includes 2,3-dimethylpyridine as the Geremoval rate enhancer. As shown, the slurry 104 composition with 500 ppm2,3-dimethylpyridine provides for a Ge R.R. of about 3,212 Å/min and anOxide R.R. of about 90 Å/min, resulting in about a 46% Ge R.R.improvement over the control slurry composition. As also shown, theslurry 104 composition with 2.00 ppm 2,3-dimethylpyridine provides for aGe R.R. of about 3,366 A/min and an Oxide R.R. of about 93 Å/min,resulting in about a 53% Ge R.R. improvement over the control slurrycomposition.

As another example, the sixth row of the table 400 illustrates a fifthexample (Example 5) which includes 2,4-dimethylpyridine as the Geremoval rate enhancer. As shown, the slurry 104 composition with 500 ppm2,4-dimethylpyridine provides for a Ge R.R. of about 3,388 Å/min and anOxide R.R. of about 91 Å/min, resulting in about a 54% Ge R.R.improvement over the control slurry composition. As also shown, theslurry 104 composition with 2.00 ppm 2,4-dimethylpyridine provides for aGe R.R. of about 3,674 Å/min and an Oxide R.R. of about 89 Å/min,resulting in about a 67% Ge R.R. improvement over the control slurrycomposition.

The seventh row of the table 400 illustrates a sixth example (Example 6)which includes 2,6-dimethylpyridine as the Ge removal rate enhancer. Asshown, the slurry 104 composition with 500 ppm 2,6-dimethylpyridineprovides for a Ge R.R. of about 3,366 Å/min and an Oxide R.R. of about92 Å/min, resulting in about a 53% Ge R.R. improvement over the controlslurry composition. As also shown, the slurry 104 composition with 2.00ppm 2,6-dimethylpyridine provides for a Ge R.R. of about 3,564 Å/min andan Oxide R.R. of about 88 Å/min, resulting in about a 62% Ge R.R.improvement over the control slurry composition.

The eighth row of the table 400 illustrates a seventh example (Example7) which includes 3,5-dimethylpyridine as the Ge removal rate enhancer.As shown, the slurry 104 composition with 500 ppm 3,5-dimethylpyridineprovides for a Ge R.R. of about 2,310 Å/min and an Oxide R.R. of about91 Å/min, resulting in about a 5% Ge R.R. improvement over the controlslurry composition. As also shown, the slurry 104 composition with 2.00ppm 3,5-dimethylpyridine provides for a Ge R.R. of about 2,354 Å/min andan Oxide R.R. of about 90 Å/min, resulting in about a 7% Ge R.R.improvement over the control slurry composition.

As described above, some embodiments of the slurry 104 may also includean etching inhibitor, for example, to further enhance CMP performance(e.g., reduced dishing). In some cases, such an etching inhibitor (e.g.,provided by the etching inhibitor source 162) may include2-mercaptopyridine N-oxide, although other etching inhibitors known inthe art may also be used. Thus, in some embodiments and by way ofexample, the slurry 104 composition may include about 2,000 ppmcolloidal silica, about 1,000 ppm H₂O₂, about 2,000 ppm2-mercaptopyridine N-oxide, about 2,000 ppm of a methylpyridine compoundor a methylpyridine derivative compound (described above), about 200 ppmpolyethylene glycol, and have a pH level of about 3. In someembodiments, the etching inhibitor includes an etching inhibitorconcentration of between approximately 100 ppm and 5,000 ppm.

Referring to FIG. 5, a table 500 shows a Ge R.R. (A/min), an Oxide R.R.(Å/min), a germanium-to-oxide selectivity, and a Ge or SiGe recess depthin angstroms (Å) for embodiments of a slurry 104 composition employingan etch inhibitor (e.g., 2-mercaptopyridine N-oxide) without a Geremoval rate enhancer versus embodiments of the slurry 104 compositionemploying the etching inhibitor together with a Ge removal rate enhancerincluding a methylpyridine compound or a methylpyridine derivativecompound. As used herein, the germanium-to-oxide selectivity is aunit-less quantity defined as a removal rate of Ge (or SiGe) divided byan oxide removal rate. For purposes of comparison, the first row of thetable 500 shows data for a control slurry composition that does notinclude the etching inhibitor or the Ge removal rate enhancer. By way ofexample, the control slurry composition may include about 2,000 ppmcolloidal silica, about 1,000 ppm H₂O₂, about 200 ppm polyethyleneglycol, and have a pH level of about 3. As shown in the table 500, thecontrol slurry composition has a Ge R.R. of about 2,200 Å/min, an OxideR.R. of about 80 Å/min, and a Ge-oxide selectivity of about 27.5,resulting in a dishing recess of about 835 Å.

With reference now to the example slurry 104 compositions having anetching inhibitor without a Ge removal rate enhancer, the second row ofthe table 500 illustrates a first example (Example 1) which includes2-mercaptopyridine N-oxide as the etching inhibitor. As shown, theslurry 104 composition which includes 2-mercaptopyridine N-oxide as theetching inhibitor, and which does not include a Ge removal rateenhancer, provides for a Ge R.R. of about 1,845 Å/min, an Oxide R.R. ofabout 28 Å/min, and a Ge-oxide selectivity of about 65, resulting in arecess of about 100 Å. Thus, as compared to the control slurrycomposition, the slurry composition of Example 1 shows an improvedGe-oxide selectivity and a reduced recess; however, the Ge R.R. is lowerthan the control slurry composition. Thus, it would be desirable to addthe Ge removal rate enhancer to slurry 104 compositions containing theetching inhibitor, for example, to improve the Ge R.R. while maintainingthe improved Ge-oxide selectivity and reduced dishing recess.

By way of example, the third row of the table 500 illustrates a secondexample (Example 2) which includes 2-mercaptopyridine N-oxide as theetching inhibitor and 2,000 ppm 2-methylpyridine as the Ge removal rateenhancer. As shown, the slurry 104 composition of Example 2 provides fora Ge R.R. of about 3,044 Å/min, an Oxide R.R. of about 50 Å/min, and aGe-oxide selectivity of about 60, resulting in a recess of about 95 Å.Thus, as compared to the slurry composition of Example 1 which does notinclude the Ge removal rate enhancer, the slurry composition of Example2 exhibits an improved Ge-oxide selectivity and a reduced recess (i.e.,reduced dishing) as well as an enhanced Ge R.R. that is greater than thecontrol slurry composition Ge R.R. While the slurry composition ofExample 2 has been shown and described to include 2-methylpyridine, itwill be understood that any of the other Ge removal rate enhancers(e.g., 3-methylpyridine; 4-methylpyridine; 2,3-dimethylpyridine;2,4-dimethylpyridine; 2,6-dimethylpyridine; and 3,5-dimethylpyridine)may also be used without departing from the scope of the presentdisclosure. In a similar manner, other etching inhibitors as known inthe art may also be used without departing from the scope of the presentdisclosure.

The various slurry 104 compositions described above, including theexample compounds and slurry compositions shown in FIGS. 2-5, mayprovide for a high Ge- or SiGe-to-dielectric material selectivity alongwith a low rate of Ge or SiGe recess formation. Among other benefits andadvantages, the slurry 104 compositions described herein including theGe removal rate enhancer provide for a high polishing throughput, a lowrate of Ge or SiGe recess formation, and an enhanced pot-life (i.e.,time period during which the slurry composition retains its efficacy).

Referring now to FIG. 6, an example of a mechanism 600 by whichembodiments of the slurry 104 composition provide their describedfunctionality is illustrated. The methylpyridine and methylpyridinederivative compounds described herein are understood to act, in variousembodiments, as reagents which serve to improve the Ge removal rate. Asshown in FIG. 6, a methylpyridine (or methylpyridine derivative)compound 602 may include one or more hydrogen atoms or hydroxyl radicalsat the benzylic position (i.e., adjacent to the benzene ring). Ingeneral, functional groups disposed at a benzylic position are morereactive than their related isolated functional groups. In someembodiments, a reaction 604 results in the methylpyridine (ormethylpyridine derivative) compound 602A which includes a more stablespecies (e.g., compared to a hydroxyl radical). Such a reaction may, forexample, help to oxidize Ge or SiGe or may form a complex with Ge orSiGe, which can enhance the dissociation rate of the oxidant. In someexamples, methylpyridine or its derivatives may not directly enhance thedissociation rate of the oxidant because the methylpyridine ormethylpyridine derivatives may co-exist with the oxidant.

Referring now to FIG. 7, illustrated therein is a method 700 of a CMPprocess in accordance with one or more of the embodiments describedherein. In various examples, the method 700 includes a CMP processhaving a high Si- or SiGe-oxide selectivity and a low rate of Ge or SiGerecess formation. It is understood that the method 700 may includeadditional steps performed before, after, and/or during the method 700.It is understood that the process steps of method 700 are merelyexemplary and are not intended to be limiting beyond what isspecifically recited in the claims that follow.

The method 700 begins at block 702 where a substrate including aGe-containing region and an oxide region, that share a common interface,is provided. By way of example, the substrate may include the substrate112. In addition, the Ge-containing region and an oxide region whichshare the common interface may include the one or more layers 118, whichdirectly face the rotating polishing pad 106. The Ge-containing regionmay include a SiGe layer having anywhere between a 15% Ge concentrationand 100% Ge concentration (i.e., pure Ge). The oxide region may includesilicon dioxide or other oxide and/or dielectrics as known in the art.The method 700 proceeds to block 704 where a CMP platen having apolishing pad disposed thereon is rotated about an axis of rotation. Forexample, the polishing pad 106 on the platen 108 may be rotated aboutthe axis of rotation 110 during operation of the CMP system 100. Themethod then proceeds to block 706 where a slurry containing a Ge removalrate enhancer is provided. By way of example, the slurry source 102 maydistribute the slurry 104 containing the Ge removal rate enhancer ontothe surface of the polishing pad 106, where the rotation of thepolishing pad 106 transports the slurry 104 underneath the substrate112. The method 700 the proceeds to block 708 where the rotatingpolishing pad 106, having the slurry 104 with the Ge removal rateenhancer dispersed thereon, is brought into contact with theGe-containing region/oxide region common interface of the substrate 112.Upon being brought into contact with the polishing pad 106, thesubstrate 112 is polished. In accordance with aspects of the presentdisclosure, the substrate 112 polishing using a slurry having the Geremoval rate enhancer provides for a CMP process with a high polishingthroughput, a high Si- or SiGe-to-oxide selectivity, and a low rate ofGe or SiGe recess formation. In addition, in some examples, the slurryused for the CMP process of the method 700 may further include anetching inhibitor, which together with the Ge removal rate enhancer, mayfurther improve the quality of the CMP process (e.g., by furtherreduction of dishing/recessing while maintaining a high Ge removalrate).

Referring now to FIG. 8, illustrated therein is a method 800 ofsemiconductor device fabrication including fabrication of a Ge or SiGeFinFET device using a CMP process with a high polishing throughput, highSi- or SiGe-oxide selectivity, and a low rate of Ge or SiGe recessformation. It is understood that the method 800 includes steps havingfeatures of a complementary metal-oxide-semiconductor (CMOS) technologyprocess flow and thus, are only described briefly herein. Additionalsteps may be performed before, after, and/or during the method 800.

FIGS. 9-13 are cross-section views, and FIG. 14 is a perspective view,of an embodiment of a semiconductor device 900 according to variousstages of the method 800 of FIG. 8. It is understood that thesemiconductor device 900 may include various other devices and features,such as other types of devices such as additional transistors, bipolarjunction transistors, resistors, capacitors, inductors, diodes, fuses,static random access memory (SRAM) and/or other logic circuits, etc.,but is simplified for a better understanding of the inventive conceptsof the present disclosure. In some embodiments, the semiconductor device900 includes a plurality of semiconductor devices (e.g., transistors),including PFETs, NFETs, etc., which may be interconnected. Moreover, itis noted that the process steps of method 800, including anydescriptions given with reference to FIGS. 9-14, are merely exemplaryand are not intended to be limiting beyond what is specifically recitedin the claims that follow.

Referring now to the method 800, the method 800 begins at block 802where a substrate including fins and isolation regions is provided. Insome embodiments, the substrate may be a semiconductor substrate such asa silicon substrate. The substrate may include various layers, includingconductive or insulating layers formed on a semiconductor substrate. Thesubstrate may include various doping configurations depending on designrequirements as is known in the art. The substrate may also includeother semiconductors such as germanium, silicon carbide (SiC), silicongermanium (SiGe), or diamond. Alternatively, the substrate may include acompound semiconductor and/or an alloy semiconductor. Further, thesubstrate may optionally include an epitaxial layer (epi-layer), may bestrained for performance enhancement, may include a silicon-on-insulator(SOI) structure, and/or have other suitable enhancement features.

In various embodiments, the substrate includes a plurality of finsextending therefrom. The fins, like the substrate, may comprise siliconor another elementary semiconductor, such as germanium; a compoundsemiconductor including silicon carbide, gallium arsenide, galliumphosphide, indium phosphide, indium arsenide, and/or indium antimonide;an alloy semiconductor including SiGe, GaAsP, AlInAs, AlGaAs, InGaAs,GaInP, and/or GaInAsP; or combinations thereof. The fins may befabricated using suitable processes including photolithography and etchprocesses. The photolithography process may include forming aphotoresist layer (resist) overlying the substrate (e.g., on a siliconlayer), exposing the resist to a pattern, performing post-exposure bakeprocesses, and developing the resist to form a masking element includingthe resist. In some embodiments, pattering the resist to form the makingelement may be performed using an electron beam (e-beam) lithographyprocess. The masking element may then be used to protect regions of thesubstrate while an etch process forms recesses into the silicon layer,thereby leaving an extending fin. The recesses may be etched using a dryetch (e.g., reactive ion etching), a wet etch, and/or other suitableprocesses. Numerous other embodiments of methods to form the fins on thesubstrate may also be used.

As an example of block 802, and with reference to the example of FIG. 9,illustrated is a semiconductor device 900 including a semiconductorsubstrate 902 and fins 904, which may be patterned and etched asdescribed above. In some embodiments, a pad oxide layer (e.g., SiO₂) anda pad nitride layer (e.g., Si₃N₄) may also be formed over the fins 904.Formation of the fins 904 also defines trenches 906 disposed between thefins 904. The trenches 906 are subsequently used to form isolationregions, such as STI isolation regions 1002 illustrated in FIG. 10. Suchisolation regions 1002 may be formed by dielectric deposition over thesubstrate 902, which fills the trenches 906, followed by a CMP processto remove excess dielectric material, planarize a top surface of thesemiconductor device 900, and thereby form the isolation regions 1002between adjacent fins 904.

In some embodiments, one or more well implants may be performed, forexample using an ion implantation process and employing a suitableN-type or P-type dopant in order to dope the fins 904 (e.g., to dope afin well region). In some embodiments the N-type dopant includesarsenic, phosphorous, antimony, or other N-type donor material. In someembodiments, the P-type dopant includes boron, aluminum, gallium,indium, or other P-type acceptor material. In some embodiments, similarN-type or P-type dopants may be used to perform anti-punch through (APT)ion implantation through the fins 904. In some embodiments, other ionimplant processes may also be performed, such as a threshold voltage(V_(t)) adjust implant, a halo implant, or other suitable implant. Afteran ion implantation process, the semiconductor device 900 may besubjected to a high temperature anneal, for example greater thanapproximately 800° C., in order to remove defects and activate dopants(i.e., to place dopants into substitutional sites).

The method 800 proceeds to block 804 where the fins are recessed and achannel region material is grown within the recessed fin regions. By wayof example, and with reference to FIG. 10, a top portion of the fins 904is recessed, resulting in recessed fins 904A. The recessing process mayinclude a dry etching process, a wet etching process, and/or acombination thereof. Continuing the example of block 804 of the method800, and referring now to FIG. 11, a device channel region material 1102(e.g., a FinFET device channel region material) is formed over an endportion of recessed fins 904A. In some embodiments, the channel regionmaterial 1102 includes a Si_(1-x)Ge_(x) layer, where the germaniumcontent ‘x’ may be in a range of approximately 15% to approximately 100%(pure Ge). In some embodiments, the channel region material 1102 mayinclude a material having a different composition than a composition ofthe recessed fins 904A on which the channel region material 1102 isformed, which may result in strain within the channel region material1102. In some examples, the channel region material 1102 may include amaterial having the same or similar composition as the composition ofthe recessed fins 904A on which the channel region material 1102 isformed. In some embodiments, channel region material 1102 is depositedusing EPI, CVD, PVD, ALD, or other suitable process.

The method 800 proceeds to block 806 wherein a CMP process is performedto remove excess channel region material and planarize a top surface ofthe device. By way of example, and with reference to FIG. 12, a CMPprocess is performed using a CMP slurry having a Ge removal rateenhancer that provides for a high Ge-oxide selectivity with a low rateof recess formation in the Si_(1-x)Ge_(x) channel region material 1102.As shown, the CMP process removes excess channel region material 1102from the substrate, resulting in channel region material 1102A, andforms a substantially planar surface along dashed line 1202. Since theslurry provides for a high Ge-oxide selectivity, as described above, theGe or SiGe channel region material 1102 is removed from thesemiconductor substrate at a higher rate than the oxide of the STIisolation regions 1002, resulting in a substantially flat top surface ofthe device 900.

The method 800 proceeds to block 808 the isolation regions are recessed.In an embodiment of block 808, and with reference to FIG. 13, the STIisolation regions 1002 (FIGS. 10-12) around the fins are recessed by aheight ‘H’. In some embodiments, recessing of the STI isolation regions1002 laterally exposes an upper portion of the fins. The STI recessingprocess may include a dry etching process, a wet etching process, and/ora combination thereof, which may be appropriately selected for a desiredrecess height ‘H’.

The method 800 proceeds to block 810 where source drain regions and agate stack are formed. By way of example, and with reference to theexample of FIG. 14, a source region 1405 and a drain region 1407 areformed in, on, and/or surrounding the fins 904. The source/drain regions1405, 1407 may be epitaxially grown over the fins 904. In variousembodiments, a transistor channel region, including the channel regionmaterial 1102A, is disposed within the fins 904 and underlying a gatestructure 1408.

Continuing with the example of block 810, the gate structure 1408includes a high-K/metal gate stack. Additionally, the gate structure1408 includes an interfacial layer 1404 formed over the channel regionmaterial 1102A of the fin, a high-K gate dielectric layer 1406 formedover the interfacial layer 1404, and a metal layer 1410 formed over thehigh-K gate dielectric layer 1406. High-K gate dielectrics, as used anddescribed herein, include dielectric material having a high dielectricconstant, for example, greater than that of thermal silicon oxide(˜3.9). The metal layer used within high-K/metal gate stack may includea metal, metal alloy, or metal silicide. Additionally, the formation ofthe gate structure 1408 includes depositions to form various gatematerials and one or more CMP processes to remove excessive gatematerials and thereby planarize a top surface of the semiconductordevice 900.

The interfacial layer 1404 may include a dielectric material such assilicon oxide (SiO₂), HfSiO, or silicon oxynitride (SiON). The high-Kgate dielectric layer 1406 may include a high-K dielectric layer such ashafnium oxide (HfO₂). Alternatively, the high-K gate dielectric layer1406 may include other high-K dielectrics, such as TiO₂, HfZrO, Ta₂O₃,HfSiO₄, ZrO₂, ZrSiO₂, LaO, AlO, ZrO, TiO, Ta₂O₅, Y₂O₃, SrTiO₃ (STO),BaTiO₃ (BTO), BaZrO, HfZrO, HfLaO, HfSiO, LaSiO, AlSiO, HfTaO, HfTiO,(Ba,Sr)TiO₃ (BST), Al₂O₃, Si₃N₄, oxynitrides (SiON), combinationsthereof, or other suitable material. The metal layer 1410 of the gatestructure 1408 may include a single layer or alternatively a multi-layerstructure, such as various combinations of a metal layer with a selectedwork function to enhance the device performance (work function metallayer), liner layer, wetting layer, adhesion layer, metal alloy or metalsilicide. By way of example, the metal layer 1410 may include Ti, Ag,Al, TiAlN, TaC, TaCN, TaSiN, Mn, Zr, TiN, TaN, Ru, Mo, Al, WN, Cu, W,Re, Ir, Co, Ni, other suitable metal materials or a combination thereof.In some embodiments, the metal layer 1410 may be formed separately forN-FET and P-FET transistors which may use different metal layers. Invarious embodiments, a CMP process may be performed to remove excessivemetal from the metal layer 1410 and thereby provide a substantiallyplanar top surface of the metal layer 1410 of the gate structure 1408.

The semiconductor device 900 may undergo further processing to formvarious features and regions known in the art. For example, subsequentprocessing may form various contacts/vias/lines and multilayersinterconnect features (e.g., metal layers and interlayer dielectrics) onthe substrate, configured to connect the various features to form afunctional circuit that may include one or more FinFET devices. Infurtherance of the example, a multilayer interconnection may includevertical interconnects, such as vias or contacts, and horizontalinterconnects, such as metal lines. The various interconnection featuresmay employ various conductive materials including copper, tungsten,and/or silicide. In one example, a damascene and/or dual damasceneprocess is used to form a copper related multilayer interconnectionstructure.

Moreover, additional process steps may be implemented before, during,and after the method 800, and some process steps described above may bereplaced or eliminated in accordance with various embodiments of themethod 800. With respect to the description provided herein, the presentdisclosure offers an improved CMP slurry composition, as well as methodsfor using such composition, which provides for a high Ge- orSiGe-to-dielectric material selectivity along with a low rate of Ge orSiGe recess formation. As described above, the disclosed slurrycomposition may include an oxidant and a Ge removal rate enhancer. Insome embodiments, the slurry composition may also include an etchinginhibitor. In some embodiments, the oxidant includes a compound havingone or more oxygen molecules. In some embodiments, the Ge removal rateenhancer includes a methylpyridine compound or a methylpyridinederivative compound. In the various embodiments described herein, theslurry compositions including the Ge removal rate enhancer provides ahigh polishing throughput (e.g., via high Ge or SiGe removal), a lowrate of Ge or SiGe recess formation, and an enhanced pot-life (i.e.,time period during which the slurry composition retains its efficacy).Those of skill in the art will readily appreciate that the methods andstructures described herein may be applied to a variety of othersemiconductor processes and/or devices to advantageously achieve similarbenefits from such other processes and/or devices without departing fromthe scope of the present disclosure.

Thus, one of the embodiments of the present disclosure described aslurry composition including an oxidant having a compound with one ormore oxygen molecules, and a germanium removal rate enhancer. Thegermanium removal rate enhancer includes at least one of amethylpyridine compound and a methylpyridine derivative compound. By wayof example, the oxidant may include at least one of hydrogen peroxide,potassium peroxodisulfate, ammonium peroxodisulfate, sodiumperoxodisulfate, potassium peroxymonosulfate, peracetic acid, andtert-butyl hydrogen peroxide. Also, by way of example, the germaniumremoval rate enhancer includes at least one of 2-methylpyridine,3-methylpyridine, 4-methylpyridine, 2,3-dimethylpyridine,2,4-dimethylpyridine, 2,6-dimethylpyridine, and 3,5-dimethylpyridine.

In another of the embodiments, discussed is a CMP system which includesa slurry source, a polishing pad, and a workpiece carrier. In someembodiments, the slurry source is configured to distribute a slurryhaving a slurry composition including an oxidant and a germanium removalrate enhancer. The germanium removal rate enhancer includes at least oneof a methylpyridine compound and a methylpyridine derivative compound.In some examples, the polishing pad is disposed on a platen that isconfigured to rotate, and the slurry source is configured to distributethe slurry onto a surface of the polishing pad. In some embodiments, theworkpiece carrier is configured to house a substrate and bring thesubstrate into contact with the polishing pad, thereby polishing thesubstrate.

In yet another of the embodiments, discussed is a method which includesproviding a substrate having a germanium-containing region and an oxideregion. In some embodiments, the germanium-containing region and theoxide region share a common interface. The CMP platen including apolishing pad disposed thereon is rotated. In various embodiments, aslurry containing an oxidant and a germanium removal rate enhancer isprovided onto a surface of the polishing pad. The rotating polishingpad, having the slurry thereon, is put in contact with the commoninterface of the germanium-containing region and the oxide region,thereby polishing the common interface.

The foregoing outlines features of several embodiments so that thoseskilled in the art may better understand the aspects of the presentdisclosure. Those skilled in the art should appreciate that they mayreadily use the present disclosure as a basis for designing or modifyingother processes and structures for carrying out the same purposes and/orachieving the same advantages of the embodiments introduced herein.Those skilled in the art should also realize that such equivalentconstructions do not depart from the spirit and scope of the presentdisclosure, and that they may make various changes, substitutions, andalterations herein without departing from the spirit and scope of thepresent disclosure.

What is claimed is:
 1. A chemical mechanical polishing (CMP) system,comprising: a slurry source configured to distribute a slurry having aslurry composition including an oxidant and a germanium removal rateenhancer, wherein the germanium removal rate enhancer includes at leastone of a methylpyridine compound and a methylpyridine derivativecompound; a polishing pad disposed on a platen that is configured torotate, wherein the slurry source is further configured to distributethe slurry onto a surface of the polishing pad; and a workpiece carrierconfigured to house a substrate and bring the substrate into contactwith the polishing pad.
 2. The CMP system of claim 1, wherein thegermanium removal rate enhancer includes the methylpyridine compoundincluding at least one of 2-methylpyridine, 3-methylpyridine, and4-methylpyridine.
 3. The CMP system of claim 1, wherein the germaniumremoval rate enhancer includes the methylpyridine derivative compoundincluding at least one of 2,3-dimethylpyridine, 2,4-dimethylpyridine,2,6-dimethylpyridine, and 3,5-dimethylpyridine.
 4. The CMP system ofclaim 1, wherein the oxidant includes a compound having one or moreoxygen atoms.
 5. The CMP system of claim 1, wherein the oxidant includesone or more of hydrogen peroxide, potassium peroxodisulfate, ammoniumperoxodisulfate, sodium peroxodisulfate, potassium peroxymonosulfate,peracetic acid, and tert-butyl hydrogen peroxide.
 6. The CMP system ofclaim 1, wherein the slurry composition further includes an etchinginhibitor.
 7. The CMP system of claim 6, wherein the etching inhibitorincludes 2-mercaptopyridine N-oxide.
 8. The CMP system of claim 1,wherein the slurry composition further includes an abrasive including atleast one of colloidal silica, fumed silica, aluminum oxide, silicashell based composite submicron particles, and ceria.
 9. The CMP systemof claim 1, wherein the slurry composition further includes at least oneof a surfactant, an organic complexant, a chelating agent, an organic orinorganic acid, an organic or inorganic base, a corrosion inhibitor, anda buffer.
 10. The CMP system of claim 1, wherein the slurry compositionincludes a slurry composition having a pH level in a range of betweenapproximately 1 and
 6. 11. An apparatus, comprising: a slurry sourceconfigured to distribute a slurry including an oxidant having one ormore oxygen atoms and a germanium removal rate enhancer including amethylpyridine-based compound; a polishing pad, wherein the slurrysource is further configured to distribute the slurry onto a surface ofthe polishing pad; and a workpiece carrier configured to house asubstrate including a surface layer, wherein the workpiece carrier isfurther configured to bring the surface layer into contact with thepolishing pad.
 12. The apparatus of claim 11, wherein the surface layerincludes at least one of Ge and SiGe.
 13. The apparatus of claim 11,wherein the surface layer further includes a dielectric layer.
 14. Theapparatus of claim 11, wherein the polishing pad is disposed on a platenthat is configured to rotate, and wherein the rotation of the polishingpad is configured to transport the slurry underneath the surface layer.15. The apparatus of claim 11, further comprising a pad conditionerconfigured to roughen the surface of the polishing pad.
 16. Theapparatus of claim 11, wherein the workpiece carrier is configured torotate.
 17. The apparatus of claim 11, further comprising a coupling toone or more valve manifold boxes that are configured to selectivelyprovide the slurry from a slurry tank to the apparatus.
 18. A system,comprising: a slurry source configured to distribute a slurry includinga germanium removal rate enhancer including a methylpyridine-basedcompound and an etching inhibitor including an N-oxide compound; and apolishing pad disposed on a platen, wherein the slurry source is furtherconfigured to distribute the slurry onto a surface of the polishing pad.19. The system of claim 18, further comprising a workpiece carrierconfigured to house a substrate and bring the substrate into contactwith the polishing pad.
 20. The system of claim 18, wherein the N-oxidecompound includes 2-mercaptopyridine N-oxide.